Picture frame



FIG. 1 is a front elevational view of a picture frame showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a right side elevational view thereof.

The broken lines in FIGS. 1 and 4 are for environmental purposes only and form no part of the claimed design. 

The ornamental design for a picture frame, as shown and described. 